Laminated Bus Bar Integration for Ripple Current Reduction
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Solution Overview
Problem
Existing power conversion devices, particularly uninterruptible power-supply systems, face challenges in reducing ripple current due to increased interphase impedance caused by fuse elements and wiring distances between inverter and converter units, which hinders downsizing and efficiency.
Innovation Solution
The use of a laminated conductor to connect power conversion units in a power converter and inverter, with adjacent placement of corresponding phases to minimize interphase impedance and synchronize triangular wave signals for PWM control, effectively reducing ripple current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuse elements are added between phases for short-circuit protection, then reliability is improved, but interphase impedance increases causing ripple current to worsen
Solution Approach 1:
The patent combines the converter and inverter into a single integrated power conversion device with shared capacitors and common DC busbars. This merging reduces the number of fuse elements needed and minimizes interphase impedance by eliminating redundant protective components between phases, thereby reducing ripple current while maintaining short-circuit protection capability.
Solution Approach 2:
The patent implements multi-functional busbars that serve both as current carrying conductors and as structural support for mounting capacitors and semiconductor modules. The DC busbars perform multiple functions including voltage stabilization, current distribution, and mechanical assembly, reducing the need for additional protective components that would increase impedance.
2Ease of manufacture
If converter and inverter are arranged as individual units, then ease of manufacture is improved, but wiring distance increases causing interphase impedance to worsen
Solution Approach 1:
The patent merges the converter and inverter into a single integrated unit where the DC busbars and capacitors are shared between both functions. This consolidation eliminates the need for separate wiring connections between independent converter and inverter units, significantly reducing wiring distance and interphase impedance while maintaining manufacturing simplicity through standardized modular components.
Solution Approach 2:
The patent nests the converter circuitry within the same physical housing as the inverter, with the DC busbars and capacitors serving both functions simultaneously. The converter's DC output terminals are directly connected to the inverter's DC input terminals through shared busbars, creating a nested configuration that minimizes external wiring while preserving modular assembly capabilities.
3Volume of moving object
If capacitance of capacitors is reduced for downsizing, then volume is improved, but ripple current increases worsening performance
Solution Approach 1:
The patent combines multiple capacitor functions into a single shared capacitor bank that serves both the converter and inverter. By merging the smoothing capacitors and DC link capacitors into common components with optimized capacitance values, the system achieves adequate ripple current suppression without requiring large individual capacitors for each function, thereby reducing overall volume while maintaining performance.
Solution Approach 2:
The patent optimizes the capacitance parameters of the shared capacitors based on the combined ripple current requirements of both converter and inverter. By calculating and setting the capacitance value to satisfy the worst-case ripple current scenario while utilizing the impedance-reducing effect of the integrated configuration, the system achieves downsizing without performance degradation.
Data Source
AI summary
An uninterruptible power-supply system is a power converter having a PN laminated bus bar and a plurality of power conversion units and supplying power from a commercial power supply via a converter and an inverter. The power conversion units each have positive side terminals connected to each other and negative side terminals connected to each other through the PN laminated bus bar. At least one power conversion unit constitutes a phase of the converter. At least another one power conversion unit constitutes a phase of the inverter and has the positive side terminal lying adjacent to and connected through the PN laminated bus bar to the positive side terminal of the corresponding power conversion unit constituting the phase of the converter and the negative side terminal lying adjacent to and connected to the negative side terminal of the corresponding power conversion unit constituting the phase of the converter.